bio

What is a virus?

– A noncellular infectious particle; needs to infect a host cell to reproduce

Describe the structure of a virus.

– Nucleic acid (DNA or RNA); capsid (protein coat); sometimes an envelope

Explain the basis of viral host specificity.

– Viral surface proteins must match specific receptors on the host cell

What are the 5 stages of the bacteriophage lytic cycle?

– Attachment; Penetration; Biosynthesis; Maturation; Release (lysis)

Describe the difference between the lytic cycle and the lysogenic cycle.

Lytic: virus immediately replicates → cell bursts;

Lysogenic: viral DNA integrates into host DNA and stays dormant before entering lytic cycle

What is a retrovirus?

– A virus with RNA as its genetic material that converts RNA → DNA inside the host

Which enzyme is associated with a retrovirus?

– Reverse transcriptase

Describe how antiviral drugs work.

– They block viral enzymes, slowing the virus’s ability to reproduce

What is the difference between a viroid and a virus?

Viroid: naked RNA, no protein coat, infects plants;

Virus: nucleic acid + capsid, infects many organisms

Describe the difference between a prion and a viroid.

– Prion: infectious protein;

Viroid: infectious RNA

What is the basic structure of a bacterium?

– Cell wall; plasma membrane; cytoplasm; ribosomes; nucleoid; sometimes flagella, fimbriae, capsule

How do bacteria reproduce?

– Binary fission (asexual splitting into two identical cells)

How is variation introduced into bacterial cells?

– Conjugation: DNA passes through a pilus; Transformation: picks up DNA from environment; Transduction: virus transfers bacterial DNA

How do archaea differ from bacteria?

– Archaea: no peptidoglycan, branched lipids, extreme environments, closer to eukaryotes, can make methane, not affected by most antibiotics; Bacteria: peptidoglycan, unbranched lipids, common environments, typical metabolism, many affected by antibiotic

What 5 events are associated with a plant’s adaptation to land?

– Embryo protection; vascular tissue; megaphylls; seeds; flowers

What are the closest living relatives of land plants?

– Charophyte green algae

Describe the alternation of generations life cycle of plants.

– Gametophyte (n) makes gametes; Sporophyte (2n) makes spores

Distinguish between vascular and nonvascular plants.

Vascular: have xylem/Phloem;larger;live in drier areas

Nonvascular: no transport tissue; small; need moist environments

Characterize and give examples of the various groups of plants. –

Bryophytes: mosses; Lycophytes: club mosses; Ferns: spores; Gymnosperms: cones; Angiosperms: fruits

What is the function of a flower?

To produce gametes and allow pollination & fertilization

What is a fruit derived from?

– The ovary of the flower

What does the seed protect?

– The embryo

Why are fungi considered saprotrophs?

– They digest dead organic matter externally and absorb nutrients

What is the general biology of a fungus?

– Hyphae: absorb food; Mycelium: network of hyphae

What is a mycelium?

– A network of hyphae

What challenges do fungi face when trying to survive in or on humans?

– Heat; dryness; immune system; bacterial competition